Although the intense distress and impairment characteristic of acute grief typically dissipates over time, for approximately 10% to 20%--that is 1 to 2 million individuals--the grief reaction is protracted and dysfunctional. This enduring, severely debilitating response to death of a significant other, now known as prolonged grief disorder (PGD), has been associated with life-threatening conditions and may persist for years if left untreated. In order to advance bereavement research and clinical work, researchers have empirically validated diagnostic criteria for PGD over the past two decades, demonstrating its construct and predictive validity. Evidence of the clinical utility of PGD has, however, been lacking. A mental disorder with clinical utility facilitates communication and effective interventions, predicts management needs and outcomes, and differentiates disorder from non- disorder and from comorbid disorders. PGD is slated for inclusion in the next International Classification of Diseases, ICD-11. In DSM-5, it is proposed as a new subtype of Adjustment Disorder and included in the Appendix for Further Study. Regardless of diagnostic manuals, however, as a newly defined and recognized disorder, it is of paramount importance to demonstrate that PGD proves clinically useful. Although the clinical utility of PGD is implied by a vast literature that has empirically demonstrated its distinctive etiology, phenomenology, course, outcomes and response to treatment, the clinical utility of the diagnosis, per se, has not been studied. This study will obtain pilot data for a large-scale field trial of PGD by examining the clinical utility (perceived need and usefulness) of this diagnosis. Phase 1 will develop 8 prototypical bereaved virtual standardized patient (VSP) cases with and without PGD (both with and without co-morbid major depressive disorder [MDD] and posttraumatic stress disorder [PTSD]; 4 cases of spousal loss and 4 cases of child loss) using key informants (8 mental health providers), who will help develop the VSP cases, clinical utility assessments, and Phase 2 recruitment strategies. Phase 2 procedures will then be piloted with 10 mental health providers. In Phase 2, we will survey a diverse sample of 100 mental health providers likely to care for bereaved individuals (e.g., psychiatrists, psychologists, social workers, grief counselors) about their attitudes regarding the clinical utility of a PGD diagnosis, ask them to diagnose 4 VSP cases, and evaluate the impact of a PGD diagnosis on their clinical recommendations for these cases. The specific aims of this study include 1) to assess the attitudes, practices, and beliefs related to the clinical utility of a PGD diagnosis among a variety of mental health professionals; 2) to evaluate the clinical utility of the proposed PGD diagnostic criteria by having a diverse set of mental health professionals diagnose patients with and without PGD, comorbid with MDD or PTSD and not, to assess user acceptability and diagnostic accuracy; and 3) to explore how mental health professionals are likely to treat individuals with PGD, both with comorbid MDD or PTSD and without. Findings from this study will inform development of a larger field trial to determine the impact of PGD on patient outcomes.